Field emission devices (FEDs) are known in the art and are commonly employed for a broad range of applications including image display devices. In some particular applications it is desirable to control the electron beam cross-section to not more than a prescribed diameter or cross-sectional area. One technique which may be employed to effect control of emitted electron beam cross-section is incorporation of a deflection electrode as part of the FED. Some deflection electrode techniques, including those of co-pending applications filed of even date herewith, assigned to the same assignee, and entitled "Deflection Anode for Field Emission Device" and "A Field Emission Device with Integrally Formed Electrostatic Lens" provide for modification of the trajectory of the aggregate emitted electron current.
Prior art field emission devices which employ deflection electrode elements typically are modulated by variations in voltages applied to an extraction electrode. The electron beam cross-section of this method is found to exhibit only a low sensitivity to variation in the extraction electrode voltages. However, the modulation technique is not preferred.
It is now known by the inventors that some performance benefit may be derived by operating a field emission image device in a different mode wherein the extraction electrode voltage is not employed as the modulating means; but only as a switching means. In this particular mode of operation, as described in U.S. Pat. No. 5,138,237, entitled "A Field Emission Electron Device Employing a Modulatable Diamond Semiconductor Emitter", filed Aug. 20, 1991, with Ser. No. 07/747,564 and assigned to the same assignee, a modulating voltage which determines a required electron emission current is operably applied to the electron emitter electrode to provide image intelligence such as, for example, a variation in image brightness. Although this method provides advantage for device operation it proves to be disadvantageous with respect to desired electron beam cross-section stability since electron beam cross-section is strongly dependent on the voltage difference between the deflection electrode and the electron emitter.
Accordingly, there is a need for a field emission device employing a deflection electrode and/or a method for forming a field emission device with an integral deflection electrode which overcomes at least some of these shortcomings.